The present invention generally relates to a method and apparatus for LCD panel power up test and more particulary, to an apparatus for power up test a LCD panel equipped with a plurality of test electrodes for connecting to a plurality of input electrodes on the LCD panel, and a method for conducting the test.
LCD panels have been widely used in desktop computers, notebook computers and other electronic devices. Along the edge portion of a glass plate of a LCD panel is provided an electrode terminal, which is usually connected to a host system circuit by electrical wires encapsulated in a flexible film for providing electrical communications between the electrode terminal and the host system circuit. The flexible film can be a flexible printed circuit (FPC) or a tape. The output signals from the host system circuit are first processed by a driver-integrated circuit (IC) and then sent to the electrode terminal for driving the pixels on the LCD panel. The driver IC, for example, can be mounted on a tape carrier of a TAB (Tape Automated Bonding) system with the input leads of the tape carrier connect the driver IC to the host system circuit, and the output leads connect the driver IC to the electrode terminal. The electrode terminal and the host system circuit are thus in signal communication through the tape carrier.
After the LCD panels are fabricated and before they are sent to a liquid crystal monitor (LCM) module for driver IC packaging and system linking, the panels are tested in a power up test for turning on the pixels of the panel to ensure that the panels function properly. The LCD panel must pass the power up test before it is packaged with driver IC. Since a high resolution LCD panel has closely spaced input electrodes in the electrode terminal, i.e., a small pitch between the electrodes, conventional method for performing the power up test by using a probe to contact the input electrodes is extremely difficult to carry out. Moreover, the test apparatus is difficult to fabricate.
Accordingly, there is a need for providing a new method for power up testing for a LCD panel.
It is an object of the present invention to provide a LCD panel power up test method and apparatus which can be used easily and at a low cost.
Pursuant to the above object, the present invention uses a power up test panel to test a LCD panel. The power up test panel includes a plurality of test electrodes for connecting to a plurality of input electrodes on an electrode terminal of the LCD panel.
In a preferred embodiment, a power up test panel includes a glass substrate and a plurality of test electrodes formed on the glass substrate. Each of the test electrodes corresponds to one of the plurality of input electrodes on the LCD panel. When carrying out the power up test, the power up test panel and the electrode terminal of the LCD panel are matched together and a pressure is applied thereon so that each of the test electrodes is in electrical communication with a corresponding input electrode on the LCD panel. The power up test panel further includes a first connecting wire and a circuit terminal formed on the glass substrate wherein the first connecting wire connects the test electrode to the circuit terminal such that the circuit terminal may communicate with an outside circuit. A second connecting wire on a flexible film can be used to connect the circuit terminal to a host system circuit. The flexible film with the second connecting wire may be a flexible printed circuit (FPC) or a tape.
The host system circuit may include a driver IC for processing signals from the host system circuit and for outputting signals to the power up test panel through the second connecting wire.
The driver IC is preferably installed on a flexible film to process signals received from the host system circuit. The assembly of the driver IC on the flexible film can be achieved by using a chip on film (COF) or TAB package.
The driver IC can also be assembled on the power up test panel for processing signals received from the host system circuit. The driver IC can be assembled on the power up test panel by using the chip on glass (COG) technology.
Pursuant to the object of the present invention, the power up test panel which has a plurality of test electrodes can be fabricated by the following steps: (1) depositing a metal layer on a substrate and patterning a circuit thereon; (2) depositing an insulating layer on the metal layer and the substrate and forming a pattern thereon to produce appropriate contact windows; (3) depositing a photoresist layer on the insulating layer and the metal layer and forming a pattern in the photoresist layer to expose an area for forming the test electrodes; (4) depositing a photo-sensitive polyimide (PSPI) layer on the photoresist layer, the insulation layer and the metal layer and patterning the PSPI layer to expose the metal circuit in the area for forming the test electrodes; (5) forming the test electrodes by depositing metal bumps on the exposed metal circuit; and (6) stripping the photoresist layer.
The substrate for forming the test panel may be a glass substrate. The formation of the test electrodes on the exposed metal circuit can be achieved by electrical plating.
The scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood that the detailed description and the specific examples, while illustrating the preferred embodiments of the invention, are given by way of illustration only, various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from the following detailed description.